Turbine construction



- K. FREY ,TURBINE CONSTRUCTION Fil-ed July l7, 1927 Nov. 13, 1928.

Patented Nov. 13, 1928.

'UNITED STATES 1,691,184 PATENT OFFICE.

KARL naar, or ENNETBADEN, SWITZERLAND, AssIeNen To AKTIENGESELLSCHAFT BROWN BOVERI 8c CIE., OF BADEN, SWITZERLAND, A JONT-STOCK COMPANY OF* SWITZERLAND.

Application inea July 7, 1927, sei-a1 No.

This invention relates to steamturbine construction, particularly to turbines ot' the double flow type, which are characterized by arrangement oi' separate steam cylinders in the same casing, the steam flowing in opposite dir ctions through the 'ditierent cylinders.

The object o'j the `present invention is `the provision of a construction whereby the tur.A bine is adapted tor operation with economical steam consumption at reducedloads, well as a i'ull load, without disturbing the thrust balance on the shaft, irrespective ot which section is being employed.

Another object is the provision of a construction which will accomplish these results and prevent overheating in the section which is not under steam.

Other and further objects will bev pointed out or indicated hereinafter upon an understanding of .theinvention or its employment in practice.

In the drawing forming a part oi3 this speciiication Fig. 1 is a diagrammatic illustration in the nature of a sectionalelevation of a double flow turbine .embodying the invention;

Fig. 2 is a detail in the nature of a longitudinal section througl'i a portion of the thrust compensating device and adjacent blade carrying portions;

Fig. 3 is a section similar to Fig. 2 but shows ing a modiiied torni of construction for the i thrust compensating device, and f Fig. 4 is a diagram illustrating the relationship ot blading in the form illustrated in Fig. 3.

It is to be understood that Vwhile the constructions here illustrated are presented as examples ofstructure in which the invention may be embodied, the invention is susceptible of incorporation in various other forms dit'- tering from these, but still within the spirit and scope of the appended claims.

In the operation of reaction turbines of the double flow type, an undesirably high steam consumption takes place it operating steam is admitted to both sectionswhen onk reduced loads. Moreover, in turbine installations containing a number o't units, and where the load tluctuates between wide limits, it is a tact of Vexperience that on the lower fractional loads large differences appear in the percentage loads taken by the individual units. This may be a great disadvantage under cer- TURBINE CONSTRUCTION.

204,120, and in Germany Jury 1.? `1926;

to a construction for turbines of the rdouble ilow type, in which the axial thrust on the shatt isbalanced, and oneotl the sections may be cut out completely, for reduction of f load without disturbing the thrust balance.

its illustrated in the accompanying drawing, the casing is constructed so as to aliord two operating cylinders or turbine sections 10 and 11 to which steam admission is had separately from admission chambers'12 and 15 at the mid-portion of the casing, the steam flowing in opposite directions-through the different cylinders to the exhaust chambers 141 and 17. Admission to chamber 12 is controlled by valve 1G, and to chamber 15 by valve 19. The rotor drums 18 and 21 for the respective cylinders are carried on the same shaft 20 and the blading 22 and 25 in both sections is arranged to actuate the drums and shaft in thev same direction. Between the two sections, the shaft carries a dummy piston 211 upon which the steam pressure in either section is effective to counterbalance the axial thrust on the rotor blades. form illustrated in Fig. 2, a seal is provided across the dummy piston by labyrinth ele` ments 26, so as tok control the leakage of steam from one cylinder to the other. When the turbine is required to work against a very high back pressure, howevenand a substantial amount of steam flow through the non-Working cylinder must be permitted, in.

order to avoid excessive windage losses and heating, a construction such as that illustrated in Figs. 3 and 4; is employed. lIn this arrangement, the flow control across the dummy piston is accomplishedby the use of a series of small auxiliary blades 27 mounted in cooperating. relationship on the dummy piston 24 and on the associated portion of the casing, said blades being arraneed to permit passage of steam from the woring cylinder to the cylinder which is cut out When op- In the f tobot erating at reduced load. /Vith proper proportion and. design, either the labyrinth or the auxiliary blade arrangement may be constructed so that the leakage from the Working cylinder kto the non-Working cylinder is just suiiicient to cover the losses of the other- Wise empty blading of the latter. In the construction illustrated in Figs. 3 and 4, the arrangement is such that the direction or iiow of steam through the auxiliary blades 27 is from the chamber 12 to the chamber 15.

In o eration at full load, steamis admitted cylinders through the valves 16 and 19. At reduced load, however, one or the other of the cylinders may be cut out of operation by the closing of its valve. Under either condition of operation, the axial thrust of the rotor blades is balanced bythe thrust on the cylinder 24. vWith either of the constructions illustrated lin Figs. 2 and 3, the leakage across the dummy pistonV is adequate to supply the losses of the non-Working cylinder, Which, in the arrangement illustrated in Figs. 3 and i Will be the cylinder 11.

This invention is of greatest utility in installations in Which high boiler pressures are employed and the `turbine works against a considerable back pressure.

Vhatl claim is:

1. In a steam turbine of the double flow type, in combination, a casing aii'ordng respective Working cylinders arranged to transmit steam in diii'erent axial directions, a common shaft served by said cylinders, blading in the cylinders arranged to induce rotation of ythe shaft in the same direction, means vfor controllingsteam admission to different cylinders independently, a thrust balancing element carried by the shaft and subjectto pressure of steam in diiierent cylinders, and

Vauxiliar blading carried by said element for controlling the iioW of steam from one cylin- Vder to another.

carried bythe shaft and subject to pressure i of steam from both admission chambers, and auxiliary blading associated With said element for controlling passage of steam from one cylinder to the other.

In testimony whereof I have hereunto subscribed my name this '24th day of June A. D. 1927, at' Zurich, Switzerland. j

KARL .FREY 

